1. Field of the Invention
The present invention relates to an antifoam powder exhibiting delayed antifoam activity, and in particular, relates to the preparation of an antifoam powder comprising a modified amino silicone/organopolysiloxane antifoam fluid absorbed in carrier filler. The antifoam powder may be used in laundry detergent formulations, especially in fabric washing, where excellent antifoaming effects are exhibited in the rinsing cycle, while maintaining similar foaming nature in washing cycles compared to detergents without antifoam. The present invention also relates to a process of synthesis of the modified amino silicone/organopolysiloxane-based delay antifoam present in the antifoam powder or antifoam fluid for use in detergent formulations.
Specifically, the present invention is thus directed not only to saving huge amounts of waste water, but also to helping to preserve massive amounts of precious clean water for desirable use and application. Advantageously, therefore the present invention in other words is in the line of green water balance targeted to reduce pollution and save the world from future massive climatic disasters or ecological imbalances.
More specifically, the modified amino silicone or organopolysiloxane in powder form or fluid form can be readily used for diverse applications such as in personal care, especially hair care, home care, textile care, and the like.
2. Description of the Art
In washing processes, water is taken by hand in a bucket or in a fabric soaking container, or in a washing tub in a washing machine. Thereafter, the desired quantity of detergent is added to generate lather by hand shaking or by running for a while in the washing tub. This is followed by immersion of the dirty fabrics for soaking for 10 to 30 min. After a soaking period, the fabric is rubbed by hand to remove dirt or the washing cycle is run for 10 to 20 min in case of machine washing.
For rinsing, the dirty water is drained, and further dirty water is removed by squeezing the fabrics. Thus each such rinsing cycle consists of squeezing the fabrics and washing the fabrics with fresh water. Such rinsing cycles are repeated for four to five times for hand washing or in case of machine washing, four to five rinse cycles are used to remove all foam before final spinning.
It is a traditional perception that the absence of foam in a washing cycle implies that the detergent is not a good one. Thus, all detergent manufacturers have a common requirement of foaming during washing and preferably not foaming during rinsing, for saving cost and water in such kinds of detergent.
Attempts have been made in the past to resolve this problem by a secondary method, called the “single rinse concept”, where during the rinsing cycle, a defoamer containing a fabric conditioner is used, the fabric conditioner conditioning the fabric during the rinsing cycle, and in addition destroying all the residual foam. This concept has not been very successful in case of the hand washing process, since the use of fabric conditioner in this class is considered to be a luxury and people of the hand-washing segment use hand washing due to monetary constraints for fabric cleaning.
Considering the waste of water and the formulation cost for normal detergents used in hand wash or machine wash, there has been a need for detergent formulations which, when used for washing fabrics, generates a preferred amount of foaming during the washing cycle without affecting the cleaning nature of the detergent, but also has antifoaming activity in the rinsing cycle so that one or two rinses is/are enough to clean the fabric. It is however extremely difficult to provide for such characteristics in detergent formulations which would favour both the washing and rinsing cycles and make washing of clothes/fabrics more convenient and user friendly apart from taking care of avoiding unnecessary wastage of valuable water and saving the environment from unnecessarily wasting of water in hand wash and/or machine washing. It is also important, that in such an advancement directed to washing formulations adapted for effective washing while avoiding waste of water, the formulations are available at cost-effective rates, since the market is highly price sensitive, and the success of new detergents heavily depends on cost as well.
U.S. Pat. No. 4,637,890 discloses a detergent composition that acts as a defoamer in rinsing cycles. Detergent compositions disclosed therein contain suds/foam-controlling prills comprising fatty acid soap, quaternary ammonium salt and silicone fluid for suds suppression. It is indicated in the patent that the prills do not dissolve in the relatively high pH (from 9 to 10.5 pH) washing cycles, and the prills are not active at high pH. Prills become active to suppress suds at low pH in the rinse cycles where less alkaline detergent is contained in the rinse water. However, the examples do not appear directed to any actual application, and additionally it is not clear whether the detergent was effective in hand washing or machine-assisted hand washing. It is understood from the disclosure that the effectiveness of suppressing foam by the silicone defoamer was highly dependent on prill formation with the help of fatty acid soap and quaternary ammonium compound. According to the disclosure a normal silicone fluid (alkylated polysiloxane) was used as the defoamer where normal silicone defoaming activity was controlled in the washing cycle by way of insolubility of prills at alkaline pH.
U.S. Pat. No. 4,894,117 discloses a composition of agglomerated granules for the delayed release of antifoaming agent in laundry systems. It particularly relates to laundry detergent compositions comprising silicone antifoams adsorbed on a powdered, water soluble carrier selected from modified cellulose carriers, which are subsequently agglomerated into granular form by mixing in the presence of a solvent for the carrier. This prior art discloses a series of granulated laundry additives wherein standard silicone antifoams were encapsulated. These different granulated laundry additives have different silicone antifoam release times depending on the type of cellulose used, and the size of the granules. It is clearly apparent that such encapsulated laundry additives are only suitable for machine washing, and totally unsuitable for hand washing or machine-assisted hand washing, since the time of washing would vary from one user to another, one region to another region and one country to another country. Thus while a detergent composition having laundry additive granules with encapsulated silicone antifoam may be acceptable to one user, it may not be suitable for the requirements of another user due to different washing time where the user can either see no foam in washing cycles due to longer washing time, or more water is used in rinsing cycle due to shorter washing time. This is due to the fact that particular granules used in the detergent for washing would have a fixed time for releasing encapsulated silicones. According to the disclosure conventional silica filled polydimethyl siloxane is used as defoamer to make encapsulated defoamer granules.
EP 254 499 B1 discloses a method for the preparation of a silicone defoamer composition, this method comprising heating a mixture comprising
a blend of organopolysiloxanes (1) and (2),
    (3) silanes or their partial hydrolysis condensates or siloxane resins,    (4) finely divided filler, preferably silica,    (5) reaction catalyst, preferably KOH,    (6) compounds like alkylene glycols, polyhydric alcohols, carboxylic acids and their esters, nonionic surfactants, polyoxyethylene anionic surfactants, polyether-modified silicones, nonionic fluorinated surfactants and OH-containing polymeric compounds like hydroxyethylcellulose. A silicone defoamer composition is obtained by reacting a blend of trimethylsilyl-terminated polydimethylsiloxane and silanol-terminated polydimethylsiloxane with polyoxyethylene-polyoxypropylene copolymers and with silica.
The defoaming activity of the composition is disclosed, but neither the use in a detergent composition is described nor can it be used as a delay defoamer by permitting foaming during the washing stage but inhibiting foaming during rinsing operations.
It is thus apparently clear from the above state of the art that all the prior art relies on encapsulation of silicone or silicone defoamer where both these types of chemicals have strong antifoaming action. The activity of delay antifoam or suppression of suds in rinsing cycles is dependent on many other parameters as discussed above. Therefore, application of such type of available antifoams is only possible in systematic washing systems like machine wash but impossible to work in hand washing or machine-assisted hand washing because of the wide variation of washing habits from one user to another. On the other hand, a product that has delayed antifoam action or suppression of suds in the rinsing cycle of hand washing or machine-assisted hand washing, obviously performs better in an all automated machine washing as well.